MRI surgical systems including MRI-compatible surgical cannulae for transferring a substance to and/or from a patient

Abstract

A cannula for transferring a substance to and/or from a patient includes a tubular support sleeve and a transfer tube. The support sleeve includes a rigid tubular member defining a lumen extending from a proximal end to a distal end of the tubular member. The transfer tube is positioned in the lumen and extends beyond each of the proximal end and the distal end of the tubular member. The tubular member includes a rigid, MRI-compatible material.

That which is claimed is: 
     
       1. A cannula for transferring a substance to and/or from a patient, the cannula comprising:
 a rigid tubular support sleeve defining a lumen extending from an inlet opening at a proximal end of the tubular support sleeve to an exit opening at a distal end of the tubular support sleeve; 
 a transfer tube positioned in the lumen and extending fully through the inlet opening, the lumen and the exit opening, the transfer tube including a proximal extension section extending beyond the proximal end of the tubular support sleeve and a distal extension section extending beyond the distal end of the tubular support sleeve; and 
 an inner sleeve disposed in the tubular support sleeve and extending beyond the distal end of the tubular support sleeve, wherein the transfer tube has a length that is greater than that of the tubular support sleeve, the transfer tube extends fully through the inner sleeve, the proximal extension section extends beyond a proximal end of the inner sleeve, and the distal extension section extends beyond a distal end of the inner sleeve; 
 wherein the tubular support sleeve comprises a rigid, MRI-compatible material; 
 wherein the transfer tube is adhered with adhesive to an inner surface of the inner sleeve; and 
 wherein:
 the transfer tube has an exit opening at a distal end of the distal extension section of the transfer tube and from which the substance is dispensed in use; 
 an exterior surface of the cannula has at least first, second and third co-axially disposed segments, an outer diameter of the second segment being greater than an outer diameter of the first segment and an outer diameter of the third segment being greater than the outer diameter of the second segment; 
 the first segment extends from the distal end of the distal extension section of the transfer tube; 
 the second segment extends between and adjoins each of the first and third segments; 
 the second segment includes a first end face defining a first step between the first segment and the second segment, the first end face projecting radially outwardly beyond the outer diameter of the first segment; 
 the third segment includes a second end face defining a second step between the second segment and the third segment, the second end face projecting radially outwardly beyond the outer diameter of the second segment; and 
 the third segment is longer than each of the first and second segments. 
 
 
     
     
       2. The cannula of  claim 1  wherein the tubular support sleeve comprises a ceramic material. 
     
     
       3. The cannula of  claim 2  including a conformal polymeric sleeve surrounding the tubular support sleeve. 
     
     
       4. The cannula of  claim 3  wherein the conformal polymeric sleeve is an elastomeric shrink tubing. 
     
     
       5. The cannula of  claim 1  including a conformal polymeric sleeve surrounding the tubular support sleeve. 
     
     
       6. The cannula of  claim 5  wherein the conformal polymeric sleeve is an elastomeric shrink tubing. 
     
     
       7. The cannula of  claim 5  wherein the conformal polymeric sleeve extends substantially coextensive with the tubular support sleeve from the proximal end of the tubular support sleeve to the distal end of the tubular support sleeve. 
     
     
       8. The cannula of  claim 1  wherein the exterior surface includes a tapered transition between the third and second segments. 
     
     
       9. The cannula of  claim 1  wherein the transfer tube is formed of fused silica. 
     
     
       10. The cannula of  claim 1  wherein the tubular support sleeve has a length of at least 10 inches. 
     
     
       11. The cannula of  claim 1  wherein an outer surface of the tubular support sleeve has a size and geometry adapted for use with a stereotactic frame. 
     
     
       12. The cannula of  claim 1  including a silicone or polyvinyl chloride (PVC) protective tubing extending from the proximal end of the tubular support sleeve, wherein the proximal extension section of the transfer tube extends through the protective tubing. 
     
     
       13. The cannula of  claim 12  wherein the protective tubing is bonded to the proximal end of the tubular support sleeve. 
     
     
       14. The cannula of  claim 1  wherein the transfer tube is a continuous unitary tube formed of fused silica. 
     
     
       15. The cannula of  claim 1  wherein:
 the first end face is the distal end of the inner sleeve; 
 the second end face is the distal end of the tubular support sleeve; 
 the first segment extends from the distal end of the distal extension section of the transfer tube to the distal end of the inner sleeve; 
 the second segment extends from the distal end of the inner sleeve to the distal end of the tubular support sleeve; and 
 the tubular support sleeve includes a tapered transition from the distal end of the tubular support sleeve to an outer diameter of the tubular support sleeve. 
 
     
     
       16. The cannula of  claim 1  wherein the inner sleeve is formed of a substantially rigid material. 
     
     
       17. The cannula of  claim 16  wherein the inner sleeve is adhered with adhesive to an inner surface of the tubular support sleeve. 
     
     
       18. The cannula of  claim 17  wherein:
 the cannula includes a conformal polymeric sleeve surrounding the tubular support sleeve; 
 the conformal polymeric sleeve extends substantially coextensive with the tubular support sleeve from the proximal end of the tubular support sleeve to the distal end of the tubular support sleeve; and 
 the tubular support sleeve comprises a ceramic material. 
 
     
     
       19. The cannula of  claim 1  wherein the inner sleeve is adhered with adhesive to an inner surface of the tubular support sleeve to thereby increase a stiffness of the cannula.